Impulse operated selector switch for alternating and direct current



E. G. BAKER ETAL 2,315,920

IMPULSE OPERATED SELECTOR SWITCH FOR ALTERNATING AND DIRECT CURRENTApril 6, 1943.

Filed Oct. 8, 1940 3 Sheets-Sheet. 1

g m'sum E CZINVEN 3 CR5.

BY fheciore Obqyarzy April 6, 1943- E. G. BAKER ETAL 2,315,920

IMPULSE OPERATED SELECTOR SWITCH FOR ALTERNATING AND DIRECT CURRENTFiled Oct; 8, 1940 3 Sheets-Sheet 2 NSUL/Y T ION INVENTOR5.

Edward G B01687" BY fizea0r6 Oqgcuvgn April 6, 1943- E. G. BAKER ETAL2,315,920 IMPULSE OPERATED SELECTOR SWITCH FOR ALTERNATING AND DIRECTCURRENT Filed Oct. 8, 1940 3 Sheets-Sheet I5 OQG QC DE INSULHT/O/V 75 gaV TIMER 62 PULSE L l/VE LINE KW MM? w HOLD RESET FELHY I Z w PatentedApr. 6, 1943 IMPULSE OPERATEI? FOR ALTERNATING RENT SELECTOR swrrcn ANDmanor CUR- Edward G. Baker and Thedore Obszarny, Ohicago, Ill.,asslgnors to Guardian Electric Manufacturing 00., Chicago, 111., acorporation of Illinois Application October 8, 1940, Serial N0. 360,282

8 Claims.

This invention pertains to selector switch devices for-mechanisms forselectively controlling the make and break" of portions of differentelectrical circuits or branches of a main circuit. switch devices ofthis type lend themselves to a relatively wide field of use in theselective con trol directly or remotely of various types of machines andapparatus.

More particularly, the present invention is directed to selector switchdevices of the type adapted to be actuated in step-by-step fashion bythe intermittent actuation of an electromagnet, operated by pulsationsof electrical current,

for selectively completing portions of one or more of a plurality ofdifferent electrical circuits, or branches of a main circuit.

One of the primary objects of this invention is to provide a novel andimproved form of selector switch of the character indicated, adapted foroperation either by alternating or direct current. Another object istoprovide a novel form of selector switch of the character indicatedadapted for operation by either alternating or direct current undercontrol of a mechanical timing device, which permits selectivecompletion and maintenance of an electrical circuit for a timedinterval.

A further object is to provide a novel form of alternating or directcurrent operated selector switch, controlled by a mechanical timingdevice, for effecting completion of a portion of a preselected circuitafter a timed interval subsequent to completion of another portion ofsaid circuit.

Still another object is to provide an improved unitary selector switchof the type indicated adapted for operation either by alternating ordirect current, under control of a mechanical timing device associatedtherewith; for effecting completion of a portion of a preselectedcircuit after a timed interval subsequent to completion of anotherportion of said circuit by adjustment of the selector switch andmaintaining said preselected circuit completed for a timed interval.

Other objects and advantages of this invention will be apparent from thefollowing description, taken in connection with the accompanyingdrawings, in which:

Figure 1 is a plan view of the unitary selector switch embodying thepresent invention.

Figure 2 is a transverse vertical sectional view through the switchdevice, taken substantially as indicated at line 2-2 on Figure 1.

Figures 3 and 4 are vertical sectional views through the switch device,taken substantially as indicated at lines 33 and 4-4 respectively onFigure 1.

Figure 5 is a front elevational view of the switch device showing theselector panel.

Figure 6 is a wiring diagram including the electrical circuits forcontrolling the operation of the Selector switch.

Referring now in detail to the drawings, the

selector switch device embodying the present invention includes a mainmounting frame 10 formed as a sheet metal stamping in a generallyU-shaped formation. This frame serves as a mounting for and totallysupports all elements constituting the switch device so as to provide aunitary structure or assembly.

Connected to the intermediate portion of the U-shaped frame I0, inspaced apart relation thereto, and forwardly thereof is a contact panelH of insulating material which is rigidly con nected to the frame [0 byscrews I2 with spacer elements l4 interposed between the panel and theframe as may be seen in the drawings. Said panel is provided with anarcuate series of spaced apart contact buttons it, with the heads ofsaid buttons exposed on the outer face of said panel and including bodyportions extending through the panel with their inner ends, projectingto the rear of said panel, serving as terminals for connection toconductor wires as indicated at H, which wires it may be understood formportions of different electrical circuits or branch circuits to beselectively controlled.

Mounted on the front face of the panel I I, concentric with the seriesof contact buttons I6, is an arcuate contact strip l9 having a terminalprojecting through the panel for connection to a conductor wire 20 forcompleting portions of the different electrical circuits including therespective contact buttons l6, as will hereinafter be described.

Said contact buttons l6 and contact strip I9 are adapted to be engagedby a pair of yielding contact arms 22 and 23 respectively as may be seenin Figures 1 and 5 of the drawings. Said arms are formed as extensionsof disc members 22a and 23a, which are mounted in engagement with eachother between a pair of insulating discs 25 and the assembly of the discmembers and the disc insulating members is fixedly mounted on the outerend of a shaft 21 which extends through the panel II and is journalledin a bearing 28 which is rigidly supported on the intermediate portionof the mounting frame It, as seen in Figure 4 of the drawings.

The inner end of the shaft projects within the frame l and has rigidlymounted thereon a ratchet wheel 30 adapted to be rotated in stepby-stepfashion for effecting similar movement A of the .contact arms 22 and 23for sequentially engaging the respective contact buttons l6. Due to thearrangement of the contact arms 22 and 23 it will be apparent that theconductor wire 20 is therefore in series with the particular conductorwire I! corresponding to the contact button engaged by the contact arm22 at a given time. In other words, when the contact arm 22 is inengagement with any one of the contact buttons IS, the portion of the.electrical circuit connected through said contact button is completedthrough the contact arm 23, contact strip l9 and the conductor wire 20.

The means for rotating the ratchet wheel 30 in step-by-step adjustmentsis accomplished by the intermittent energization of an electro-magnetrelay 32 supported on one of the legs of the U-shaped frame ill by meansof a bracket 33 which constitutes a lateral extension of the field piece34 of said relay. As may be seen in the drawings, said relay 32 isdisposed with its coil in an upright position and hingedly mounted onthe upper end of the upright leg of the field piece 34 is an armature 36normally urged in an upward direction away from the core 32a of the coilof the relay by means of a coil spring 31 which is connected to the rearor heel end of the armature and to a lug extension on the leg of thefield piece 34, as seen in Figure 3 of the drawings.

Pivotally mounted at 39 on a vertical axis on top of the armature 36adjacent said hinged connection thereof is an actuating pawl 40 formedof fiat bar stock and supported directly upon the top of the armatureand extending in a direction parallel to the axis of the ratchet wheel30. The forward end of said bar beyond the armature is twisted at rightangles with respect to the main body of the bar so that the lower edgeof the projecting portion of said bar is disposed adjacent the toothedperiphery of the ratchet wheel 30. The lower edge of the bar 40 inalignment with the ratchet wheel 30, is cut at an incline as indicatedat 40a to form a tooth-like surface for insuring proper engagement withthe teeth of said ratchet wheel 30. Due to the pivotal connection 39 ofsaid actuating pawl 40 to the armature, said pawl is permitted lateralmovement with respect r to the armature.

In order to maintain said actuating pawl in proper position on thearmature and for limiting its-extent of lateral movement, we provide aguide in the form of a strap 42 extending over the actuating pawladjacent the outer or free end of the armature. Said strap is secured tothe armature by means of a pair of spaced apart studs indicated at 43.

It is to be understood that relay 32 is adapted to be intermittentlyenergized by pulsations of electrical current which through the actionof its armature imparts a step-by-step action to the pawl 40 and ratchetwheel 30 for shifting contact arms 22 and 23 in a step-by-step manner sothat arm 22 is sequentially stepped over a series of contact buttons l6corresponding to the number of electrical impulses imparted to the coilof the relay 32. It is to be understood that said pulsations of currentmay be supplied directly, or from a remote sending station, and in thelatter case suitable receiving apparatus may be employed for use intransferring the wave impulses directly to the relay. Therefore, forconvenience said relay 32 will hereinafter be termed a "stepping relay.

The actuating pawl 40 is dimensioned so that its extreme outer endprojects into an on opening Illa formed in the intermediate portion ofthe U-shaped mounting frame l0. Mounted on the outer face of saidportion of the frame in registration with said opening, is an adjustableguide block Mb, having a slot or window formed therein for receiving theextreme end portion of the actuating pawl, as may be seen in Figure 3.It is to be understood that said block llb is adapted to be adjustedwith respect to the opening Illa for limiting the extent of vertical andlateral movement of the actuating pawl incident to the movement of thearmature toward and away from the core of the relay 32. The purpose ofproviding for lateral movement of the actuating pawl is to permit saidpawl to readily accommodate itself to the contour of the ratchet wheelduring vertical movement of the pawl in stepping the ratchet wheel andthereby precludes binding of sad pawl and the ratchet wheel which wouldotherwise occur due to the particular relationship of the pawl to theratchet wheel.

To insure proper return of the actuating pawl to a starting position forengaging the next tooth of the ratchet wheel for obtaining successivestepping action, we provide a coil spring 45 which is connected at oneend to the outer end of the pawl and at the other end to a stud HIcsecured to the inside of the intermediate portion of the main frame I0,adjacent the upper end thereof, so that the spring is disposed at anoblique angle, tending to draw the actuating pawl in an'upward andinward direction with respect to the ratchet wheel.

As above set forth, it is intended that the se lector switch beconstructed in a manner so that the portion of the circuit completed byengagement of contact arm 22 with a certain contact button 15,corresponding to the circuit selected, be maintained for only a shortperiod of duration, after which the switch device is caused to bereadjusted to a neutral or starting position. In order to accomplishthis function, a check pawl is pivotally mounted at 5| on the inside ofthe front or intermediate portion of the frame 10 adjacent the loweredge. Said pawl includes a sharp angularly formed nose 52 for engagementwith the teeth of the ratchet wheel 30. The opposite end of the pawlterminates in an arm 53 to which is connected a coiled spring 54, theopposite end of which spring is connected to the lower portion of theadjacent leg of the frame ID, as seen in the drawings. The function ofthe spring 54 is to normally urge the pawl 50 in a direction to causethe nose portion 52 thereof to engage the teeth of the ratchet wheel 30and to serve to check or hold the ratchet wheel in various steppedpositions of adjustment, but permitting further step-by-step adjustmentof said ratchet wheel, by the action of the actuating pawl 40.

Said check pawl 50 is normally held out of engagement with the ratchetwheel 30 by means of a holding and reset relay" 56 which is mounted onthe leg of the U-shaped frame I opposite to that upon which relay 32 ismounted. Said relay 56 is termed a holding and reset relay forconvenience in description and because of the nature and function ofsaid relay as will hereinafter be set forth. Relay 55 is disposed inopposite relation to relay 32 and has its armature 51 disposed at thelower end of the coil of the relay and hingedly connected at one end ona field piece 58. The armature 51 is normally urged in a downwarddirection to the position seen in Figure 4 of the drawings by means of acoil spring 59 which is connected to the heel end of the armature and toan extension lug on the field piece 58. Connected to and extendinginwardly from one end of the check pawl 58 is a relatively rigid rod 6|having an angularly bent offset portion positioned to engage beneath aninsulating panel 62 secured to the lower surface of said armature 51.

It is to be understood that spring 59 of the armature 51 exerts agreater force than spring 54 of the check pawl so that the armature 51is normally maintained, when the coil of the relay is deenergized, inthe position seen in Figure 4 of the drawings, and due to the engagementwith the rod 6| said armature holds the check pawl 50'out of engagementwith ratchet wheel -30 as seen in Figure 2 of the drawings. As willhereinafterhe described, relay 56 is energized during the period thatrelay 32 is'being energized by .pulsations of electrical current forimparting step-by-step action, through the pawl 48, to the ratchet wheel38 and contact arms 22 and 23.

In order that the selector switch may be readjusted to a neutral orstarting position after each adjustment for completing a preselectedcircuit, the ratchet wheel 30 is yieldingly urged in a counter-clockwisedirection, or in other words, in a direction opposite to the directionof rotation caused by the stepping action of the pawl 48. For thispurpose we provide a coil spring 65 which surrounds a portion ofthebearing 28 within the frame In with one end of the I spring extendingthrough an aperture id in the intermediate portion of said frame and theopposite end of the spring anchored on a pin 38a carried on the adjacentface of the ratchet wheel. It will now be apparent that as the ratchetwheel is stepped by the pawl 48, spring 65 becomes tensioned, so thatupon release of the ratchet wheel by disengagement of the check pawl 56,said spring 65 tends to rotate the ratchet wheel in opposite directionto a starting or neutral position. The ratchet wheel is arrested at anormal or starting position which corresponds also to the startingposition of the contact arm 22, as seen in Figure 5 of the drawings, bymeans of a nubbin 38b carried on said wheel and adapted to engage aprojecting shelf portion 66 I of a bracket 61 adjustably mounted on theinner surface of the intermediate portion of the U- shaped frame l sothat when the nubbin engages said shelf portion, the ratchet wheel willbe adjusted at a neutral or starting position with the contact arm 22likewise disposed in a neutral or starting position.

.Associated .with the respective relays 32 and 56 are switch devicesconnected in electrical circuits in amanner for controlling the make andbreak of a preselected electrical circuit which as above mentioned maybe one of a number of main electrical circuits or one of a. number ofbranch electrical circuits forming a part of the main circuit, and whichpreselected circuit corresponds to the circuit completed through thecorresponding contact buttons l6, when engaged by contact arm 22, due tothe step-by-step actuation of the ratchet wheel, as above described.

It is to be understood that each of the different branch or mainelectrical circuits to be controlled, including the respective contactbuttons 16, also include suitable'mechanism adapted to be electricallyenergized or operated. For convenience in illustration, we haverepresented in the wiring diagram in Figure 6 of the drawings aplurality of branch circuit portions connected to the respective contactbuttons l6, with each oi. said branch portions shown as including awinding or coil indicated generally at 18, which coil, it may beunderstood, may represent any suitable form of electrically, energizeddevice adapted to be operated when the particular branch circuit iscompleted through its corresponding contact button by contact arm 22.

The switch devices associated with the respective relays will now bedescribed. Mounted on a bracket 12 attached to one of the legs of theU-shaped frame I 0, immediately above the stepping relay 32, are twosets of switches composed 'of switch fingers l3, l4, and I5, 16respectively. In the normal inoperative position of the selector switch,switch fingers l3 and 14 have their contact buttons 13a and 14aoperatively engaged, while switch fingers l and 16 have their contactbuttons 15a and 16a separated, as seen in Figure 3 of the-drawings.Associated with the respective switch fingers I3, I4 and 15, are springstrips 18 for reenforcing said fingers and serving to increase thespring action thereof for urging them to return'to a normal position.

Said switch fingers and strips are mounted between a multiplicity ofblocks 19 of insulating material mounted directly upon said bracket 12.Connected to the outer end of switch finger 13 is a plug of insulatingmaterial 88 adapted to seat directly upon an arm 82 of a clock typemechanical timing mechanism which is indicated generally at 83. Theouter end of switch arm 16 is also provided with a plug of insulatingmaterial 84, the lower end of which is adapted to be engaged by the endof switch finger 14, when the latter is moved .to the position seen inFigure 3, by engagement therewith by switch fingers 13, incident to theupward movement of said switch finger through plug 88, by the arm 82 ofthe timer as will hereinafter be described.

The hold and reset relay 56 has associated therewith a normally openswitch including contact fingers and 86, the former being mounted on theinsulating member 62 and the latter being mounted between blocks Offinsulating material indicated at 81 carried on an extension of the fieldpiece 58, as seen in Figure 4 of the drawings. When the armature 51 ismoved into engagement with the core 56a of said relay 56 contact finger85 is thereby moved into operative engagement with contact finger 86 tocomplete a portion of an electrical circuit.

The mechanical timing mechanism designated at 83 is of a conventionalform and is carried on a mounting plate 88 which is secured by screws 89to the outer surface of the leg of the frame I, upon which relay 32 ismounted. .While the details of construction of the timing mechanismconstitute no part of the present invention it is believed helpful to abetter understanding of the entire operation of the selector switch topoint out that the arm 82 of the timing mechanism is the main controlmember thereof, actuated in one direction by the armature 36 as willhereinafter be described. Mounted on said arm is a pivoted pawl 90 whichis urged by means of a spring 9| into engagement with the toothedperiphery of a ratchet wheel 92 of the mechanism so that as saidoperating arm 82 is moved in a downward direction by armature 36, thepawl 90 cams over the teeth of the ratchet wheel,

but upon upward direction of movement of said am said pawl tends torotate the ratchet wheel 92, and the gearing associated therewith. Acoiled spring 84 is connected at one end to said arm 82 and at the otherend to said mounting plate 88 in a position for normally urging the arm82 in an upward direction, under control of the gearing driven by theratchet wheel 82.

As may be seen in the drawings, said operating arm 82 is normallydisposed in. a position immediately beneath and in engagement with thelower end of the plug 88, associated with switch finger 13. Said arm isadapted to be moved in a downward direction incident to the attractionof the armature 38 to the core 32a of the relay 32, and for this purposethe strap 42 for holding the actuating pawl 88 confined on the armatureincludes a forwardly extending leg 42a, positioned to extend immediatelyabove said operating arm 82 so that when said armature is attracted tothe core of the coil of the relay 32, said arm 82 is moved downwardly,and when said arm is freed of the pressure of the armature, through theleg extension 42a, said arm is drawn upwardly by the coiled spring 88under control of the gearing of the timer mechanism.

It is to be understood that the gearing of the timer mechanism and thetension in the coil spring 94 are so corelated that when the arm 82arrives at the position seen in Figure 2 of the drawings, the forces aresubstantially balanced. In other words, the position of the parts isthen such that the arm 82 has imparted sufficient movement to plug 88for shifting switch finger 13 into engagement with switch finger 14 andthe latter through the plug 84 has moved switch finger 16 out ofengagement with switch finger 15, as seen in Figure 3 of the drawings.

It will be apparent that during the period of pulsating action of thearmature 38, due to the intermittent energizing of relay 32 bypulsations of current, the operating arm 82 of the timing mechanism issubstantially held in a position out of engagement with the plug 88 sothat switch fingers 13 and 18 are in open position, while switch fingersand 18 are in engagement to complete portions of an electrical circuit.

This delay action of arm 82 as regards the switches composed of fingers13, 18 and 15 and v 18 is due to the gearing of the timing mechanism awhich requires an interval of time for return of the arm 82 to itsuppermost normal position, substantially in excess of the time betweenpulsations of current imparted to the relay 32. fore, the arm 82 ispermitted to move upwardly under timing control of the gearing whenpulsations of current to the relay 32 cease, and effects a time delayaction of the switches.

It will now be seen from the wiring diagram represented in Figure 6 thatthe switches composed of switch fingers 13 and 14 and 85 and 88,respectively, are connected in series in the main electrical circuit,while the switch composed of switch fingers 15 and 16 controls thesupply of current to the "hold and reset relay 58 from an auxiliarycircuit which for convenience may be a low voltage circuit. If desired,the main electrical circuit could be connected as a part of the lowvoltage circuit but generally the main circuit is preferably of highervoltage for the proper operation of the devices to be actuated in thebranch circuits of the main electrical circuit.

The circuits of the selector switch will now be briefly described asfollows. The coils 18 are Thereshown connected in the branch circuits ofthe main supply circuit which includes conductors designated as lines #Iand #2. This circuit includes a main conductor wire I88 for connectingthe current supply line #I to the switch finger 13 and a conductor wireI8I connects switch finger 14 to switch finger 85, and a conductor I82connects switch finger 88 to the conductor wire 28, which is connectedto the contact strip I9, throughcontact arm 23 to the contact arm 22, toa predetermined contact button I8, corresponding to the preselectedbranch circuit to be energized. Conductor wires I1 complete the branchcircuits through the respective coils 18 to the other main currentsupply line #2.

When the selector switch is in inoperative position no current ispermitted to flow through the main circuit including conductor wiresI88, Ill, I82 and the supply lines #I and #2 since the switch composedof members 85 and 88 is normally in open position. While pulsations ofelectrical current are imparted to the stepping relay 32 for effectingselective adjustment of the contact arm 22 with a desired contact buttonI8 by the action above described, the main circuit, due to operation ofthe switch fingers 13 and 18, remains open during the period thatpulsating current is supplied to said relay 32.

As above mentioned, said switch fingers 13 and 14 become separated dueto the attraction of the armature 36, through the leg extension 42a ofthe guide strip on said armature engaging the arm 82 of the mechanicaltiming device, so that said arm relieves the pressure on the lower endof the plug 88 and thereby permits switch finger 13 to yieldingly moveout of engagement with its cooperating finger 18, and which, as alsoabove mentioned, permits closing the switch composed of switch fingers15 and 18, which results in energizing the hold and reset relay 58 whichis connected in an auxiliary circuit including conductor wires I85, I88and I81. Energizing of said relay 58 attracts armature 51 and movesswitch finger 85 into engagement with finger 88 for completing a portionof the main circuit.

It will now be apparent that no current is permitted to flow through themain circuit including conductor wires I88, IM and I82, and lines #I and#2 during the period that the contact arm 22 is being stepped from onecontact button to another.

Due to the fact that relay 58, as above mentioned, functions as a "holdand reset relay" and is energized during the time that pulsations ofcurrent are being supplied to the stepping relay 32, the check pawl 58is freed by the armature 51, which is attracted to the core 580 of thecoil of the relay 58, and thereby disengages the rod 6| so that the pawl58 under influence of spring 54 operatively engages the teeth of theratchet wheel 38 and maintains the same in stepped positions ofadjustment.

Immediately upon cessation of pulsations of current being supplied tothe relay 32, the armature 88 is released and moves to its upper freeposition by coil spring 81, and such movement of the armature throughthe leg extension 8211 frees the operating arm 82 of the mechanicaltiming device 88 so that said arm 82 in a time delay action, after lapseof an interval of time, again forcibly engages the lower end of plug 88and moves switch finger 13 into engagement with switch finger 14,thereby completing the preselected electrical circuit, including themain electrical circuit, for a predetermined timed interval which timedinterval is determined by the mechanical timer 83. As said arm 82continues to move upwardly, after completion of a preselected circuitthrough the switch fingers 13 and H, motion is transmitted throughswitch finger H and plug 84 for moving the switch finger I6 out ofengagement with switch finger l5, and

when this takes place the auxiliary circuit for" member 62 reengages thearm 6|, associated with the check pawl 50, and thereby shifts said pawlout of engagement with the ratchet wheel 30,

whereupon the spring 65 then returns the ratchet wheel together with thecontact arms 22 and 23 to normal or neutral starting position.

The construction represented in the drawings may be understood tobeespecially suitable for use with alternating current, and for thispurpose the stepping relay" 32 is provided at its head with a copperslug 320, the function of which is to act as a shading ring foreliminating chatter and buzzing. It is to be understood, however, thatwhen this selector switch is intended for use with direct current, thestepping relay 32 shall be of modified form having propercharacteristics for use with direct current.

It will now be apparent that by virtue of the construction describedthere will be no arcing as a result of the contact arm 22 moving fromone contact button to another during the stepping action since nocurrent flows through the main electrical circuit, including the branchcircuits, until the selector arm is arrested for a short interval oftime in engagement with a predetermined contact button of a preselectedcircuit, after which period of time current is permitted to flow throughsaid preselected circuit for a limited period of time, under control ofa mechanical timing device, and after which all circuits are then brokenand assume a normal inoperative condition.

Although we have herein shown and described a preferred embodiment ofour invention, manifestly it is capable of modification andrearrangement of parts without departing from the spirit and scopethereof. We donot, therefore, wish to be understood as limiting thisinvention to the precise form herein illustrated and described. exceptas it may be so limited in the appended claims.

We claim as our invention:

1. In a selector switch, the combination of a plurality of contactsconnected in separate branches of a main electrical circuit, a movablecontact arm, means for shifting said arm into engagement with apredetermined one of said contacts for completing a portion of apreselected branch circuit, switch means for controlling said mainelectrical circuit, and mechanical timing means for controlling saidswitch means, said timing means and first mentioned means beinginterconnected to effect energization of said timing means uponoperation of said first mentioned means, and said timing means beingrendered operable upon discontinuance of operation of said all) firstmentioned means, whereby said switch means is controlled to eiTectenergization of the preselected branch circuit in delayed timedrelation, subsequent to engagement of said arm with the contact of thepreselected bra-nchcircuit.

2. In a selector switch, the combination of a plurality of contactsconnected in separate branches of a main electrical circuit, a movablecontact arm, means for shifting said arm into engagement with apredetermined contact for completing a portion of a preselected branchcir-' cuit, a pair of switches connected in series in the main circuit,one of said switches being normally open and the other normally closed,a separate normally open switch connected in an auxiliary circuit, anelectro-magnet in said auxiliary circuit for controlling said normallyopen series switch, and mechanical timing means for controlling theother two switches in such correlation to each other as to cause theauxiliary switch and electromagnet of the auxiliary circuit to becontrolled during an overlapping interval of the two series switches,said timing means being responsive to and operated by said firstmentioned means, whereby said switches are controlled in a manner toeffect energization of the preselected branch circuit for apredetermined limited time, in de layed timed relation, subsequent toengagement of said arm with the contact of the preselected branchcircuit.

3. In a selector switch, the combination of a plurality of contactsconnected in separate branches of a main electrical circuit, a movablecontact arm, electrical impulse operated electromagnetic means forshifting said arm in step-bystep fashion into engagement with apredetermined contact for completing a portion of a preselected branchcircuit, switch means for controlling said main electrical circuit, andme chanical timing means for controlling said switch means, said timingmeans being responsive to and rendered operable by said electro-magneticmeans, whereby said switch means is controlled to effect energization ofthe preselected branch circuit in 4. In a selector switch, thecombination of a 4 plurality of contacts connected in separate branchesof a main electrical circuit, a movable contact arm, electrical impulseoperate-d electromagnetic means for shifting said arm in step-bystepfashion into engagement with a predetermined contact for completing aportion of a pre selected branch circuit, a pair of switches connectedin series in the main circuit, one of said switches being normally openand the other normally closed, a separate normally open switch connectedin an auxiliary circuit, an electro-magnet in said auxiliary circuit forcontrolling said normally open series switch, and mechanical timingmeans for controlling the other two switches in such correlation to eachother as to cause the auxiliary switch and electro-magnet of theauxiliary circuit to be controlled during an overlapping interval of thetwo series switches, said timing means being responsive to and operatedby said first mentioned means, whereby said switches are controlled in amanner to efiect energization of the preselected branch circuit for apredetermined limited time, in delayed timed relation, subsequent toengagement of said arm with the contact of the preselected branchcircuit.

5. In a selector switch, the combination of a plurality of contactsconnected in separate branches of a main electrical circuit, a movablecontact arm, means for shifting said arm into engagement with apredetermined contact for completing a portion of a preselected branchcircult, a pair of switches connected in series in the main circuit, oneof said switches being normally open and the other normally closed, aseparate normally open switch connected in an auxiliary circuit, anelectro-magnet in said auxiliary circuit and arranged for controllingsaid normally open series switch, the other two switches beinginterconnected for correlated actuation, and mechanical timing means forcontrolling said other two switches, in such correlation to each otheras to cause the auxiliary switch and electro-magnet of the auxiliarycircuit to be controlled during an overlapping interval of the twoseries switches, said timing means being responsive to and operated bysaid first mentioned means, whereby said switches are caused to beactuated in a manner for effecting energization of the preselectedbranch circuit for a predetermined limited time, in delayed timedrelation, subsequent to engagement of said arm with the contact of thepreselected branch circuit.

6. In a selector switch, the combination of a plurality of contactsconnected in separate branches of a main electrical circuit, a movablecontact arm, electrical impulse operated electromagnetic means forshifting said arm in step-bystep fashion into engagement with apredetermined contact for completing a portion of a preselected branchcircuit, a pair of switches connected in series in the main circuit, oneof said switches being normally open and the other normally closed, aseparate normally open switch connected in an auxiliary circuit, anelectromagnet in said auxiliary circuit and arranged for controllingsaid normally open series switch, the other two switches beinginterconnected for correlated actuation, and mechanical timing means forcontrolling said other two switches in such correlation to each other asto cause the auxiliary switch and electro-magnet of the auxiliarycircuit to be controlled during an overlapping interval of the twoseries switches, said timing means being responsive to and operated bysaid impulse operated electro-magnetic means, whereby said switches arecaused to be actuated in a manner for effecting energization of thepreselected branch circuit for a predetermined limited time, in delayedtimed relation, subsequent to engagement of said arm with the contact ofthe preselected branch circuit.

I. In a selector switch, the combination of a plurality of contactsconnected in separate branches of a main electrical circuit, a movablecontact arm, electrical impulse operated electromagnetic means forshifting said arm in step-bystep fashion into engagement with apredetermined contact for completing a portion of a preselected branchcircuit, a pair of switches connected in series in the main circuit, oneof said switches being normally open and the other normally closed, aseparate normally open switch connected in an auxiliary circuit, anelectromagnet in said auxiliary circuit and arranged for controllingsaid normally open switch of said pair of switches, the other twoswitches being interconnected for correlated actuation, and mechanicaltiming means responsive to and operated by said impulse operatedelectro-magnetic means, said timing means being positioned forcontrolling said other two switches in such correlation to each other asto cause the auxiliary switch and electro-magnet of the auxiliarycircuit to be controlled during an overlapping interval of the twoseries switches, whereby said timing means is caused to be energizedduring actuation of the impulse operated electro-magnetic means andrendered operative after cessation of operation of said impulse operatedelectro-magnetic means to effect energization of the preselected branchcircuit for a predetermined limited time, in delayed timed relation,subsequent to engagement of said arm with the contact of the preselectedbranch circuit.

8. In a unitary self-contained selector switch, the combination of aplurality of contacts connected in separate branches of a mainelectrical circuit, a movable contact arm, electrical impulse operatedelectro-magnetic means for shifting said arm in step-by-step fashioninto engagement with a predetermined contact for completing a portion ofa preselected branch circuit, a pair of switches connected in series inthe main circuit, one of said switches being normally open and the othernormally closed, a separate normally open switch connected in anauxiliary circuit, an electromagnet in said auxiliary circuit andarranged for controlling said normally open switch of said pair ofswitches, the other two switches being interconnected for correlatedactuation, and clockwork type mechanical timing means having an armpositioned to be engaged by the armature of said impulse operatedelectro-magnetic means, said arm of the timing means being so positionedto control operation of said other two switches in such correlation toeach other as to cause the auxiliary switch and electro-magnet of theauxiliary circuit to be controlled during an overlapping interval of thetwo series switches, whereby said mechanical timing means is caused tobe energized during actuation of the impulse operated electromagneticmeans and rendered -operative after cessation of operation of saidimpulse operated electro-magnetic means to effect energization of thepreselected branch circuit for a predetermined limited time, in delayedtime relation, subsequent to engagement of said contact arm with thecontact of the preselected branch circuit.

EDWARD G. BAKER. THEDORE OBSZARNY.

